DIY CO2- not doing anything - The Planted Tank Forum
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post #1 of 9 (permalink) Old 08-05-2013, 03:35 AM Thread Starter
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DIY CO2- not doing anything

A week ago I set up a DIY CO2 system. It's a 2L soda bottle, a little over halfway filled with water, 2 cups of sugar, and I think it was a half teaspoon of yeast. and I drilled a hole in the cap, put the tube in the hole, and used a hot glue gun to seal it on both sides. then I connected that tube to a hole drilled in a smaller bottle which is full halfway. that tube is in the water, glued to the cap as a seal. Then a second tube comes out of that bottle (only a small bit extends into the small bottle, not in the water. Then from there I put a check valve (yes, going in the right direction) and at the end of that tube I put an airstone and put it in the tank. Well, it's been a week and nothing is happening... should there be? Did I do something wrong?
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post #2 of 9 (permalink) Old 08-05-2013, 05:18 AM
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You should notice co2 bubbles coming from the air stone within 1-2 hours if done correctly, sounds like you have a bad batch. Here's what I do when I use diy co2....

I add 2 cups of sugar to the 2 liter bottle then fill 75% of the bottle with warm water and shake it until it looks like most of the sugar has "gone away". Then I'll use a bowl, fill it with the yeast, add about a tablespoon of sugar, and 1/2 cup of warm water and mix the hell out of it. Let the yeast mix sit for 10-15 minutes to ferment, and once I see the mixture is covered with what looks like foam then I pour the mixture into the 2 liter bottle, and shake it up. Then hook up everything to my tank, and normally within about 30-45 minutes I start seeing co2 bubbles coming from the airstone. Works every time for me....
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post #3 of 9 (permalink) Old 08-05-2013, 04:24 PM
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Your problem might be the check valve.

I had a DIY CO2 setup months ago and I ran into the same problem. If you've got extra air tubing, try setting up without the check valve, AND air stone! Just put the air line into the water and monitor it. If within 10-15 minutes you get bubbles flowing into the water, your CO2 mixture works. Then, add the check valve. If you still get bubbles, then add the air stone. See where we're going with this? Trust me, I had to do it this way to narrow down the cause.

I got bubbles with no check valve or air stone, so I researched. Here's the thing - DIY CO2 does not produce enough pressure to open up the one direction check valves. It's the same case with air stones. The issue is that a lot of check valves and air stones are too air tight by design and need a good bit of pressure. Try it - blow into one end of your air stone and check valve. I got 3 different check valves and 4 different air stones that wouldn't work, till I got an air pump and rigged something up to force the gas through.

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post #4 of 9 (permalink) Old 08-05-2013, 07:00 PM
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I agree it could be the check valve. I used a nice brass one and it needed a higher working pressure than what the DIY system could provide. It should release a lot of pressure if you try to take it off. If it doesn't, you likely have a bad batch but you can verify this by sticking the tubing in a glass of water and checking to see if you are getting air bubbles (should be 1 or more per second).
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post #5 of 9 (permalink) Old 08-06-2013, 09:21 PM
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I ran into this problem 2 times before. Its not your solution. Its your second bottle. Eliminate the second bottle and just use the 2 liter bottle do not forget to put the check valve on that hose from the 2 liter bottle.
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post #6 of 9 (permalink) Old 08-07-2013, 01:03 AM
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i had a co2 set up i made with 2 20 oz gatoraide bottles. it worked great for about 4 months, (re doing the sugar yeats every 2 weeks) then all sudden i couldnt get the set up to do anything,

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post #7 of 9 (permalink) Old 08-19-2013, 03:14 AM Thread Starter
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Ok, thanks everyone! I will try those suggestions.
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post #8 of 9 (permalink) Old 08-19-2013, 06:53 PM
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Hm...this thread makes me want to try DIY CO2 for the new tank...
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post #9 of 9 (permalink) Old 08-19-2013, 11:36 PM
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I found the best method to hole the cap is with a hot gun tip, and pull hosing through it with pliers. If you are not able to do this then it's probably a leak due to backpressure.
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